Grasslands and Grassland Plants
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Unit I – Grasslands and Grassland Plants Lesson 2: Plant Classification comes, its pattern of growth begins again. Many forages and pasture crops are perennials. Trees and shrubs are Grasslands are useful due in part to the wide variety also perennials. of plants that are found in them. The main feature of grassland agriculture is its dependence on grassland plants. In classification by plant type, plants are categorized By understanding the different plant types, increasing the according to the physical characteristics of the plant. Each benefits to livestock and wildlife from the grassland is species within a plant type has characteristics that are possible. A thorough knowledge of the various types similar to all other species of the same plant type. Four and life cycles of these plants is important to grassland different plant types are found in grasslands—grasses, management. legumes, forbs, and woody plants. Grassland Plant Classification Grasses of the Grassland A grassland may include a great variety of different plant Grasses are one of the four dominant plant types found species. All grassland plants can be classified according to in a grassland. They serve many purposes, such as food for two different criteria—life cycle and plant type. livestock and wildlife (orchardgrass, fescue, and alfalfa), food for humans (cereals and grain sorghum), and erosion Classification by life cycle divides plants based on their prevention. yearly growth and seeding characteristics. Each plant grows in stages which, from beginning to end, comprise The grasses of the Great Plains are herbaceous, or without its life cycle. A plant’s life cycle is closely related to its woody stems. The stems, or culms, of grasses are usually productivity and is therefore extremely important. Plants hollow and therefore resist compaction. Leaves or blades can be divided by their life cycles into three categories: connect directly to the culm at a sheath, which surrounds annuals, biennials, and perennials. the stem. All leaf blades have a distinctive parallel venation in which the veins run side by side along the length of Annual plants complete their life cycle within one year the blade of grass. These visual characteristics make or growing season. They die after producing seed and it possible to separate the grasses from all other plant will not grow again the next year unless self-seeded or species. Notice the characteristics of the grasses pictured planted again. Corn, cheat, and crabgrass are examples of in Figure 2.1. annual plants. Biennial plants require two years to complete their life Figure 2.1 – Characteristic Grasses: Indiangrass, cycle. Generally, the plant produces mainly vegetative Orchardgrass, Switchgrass growth, including leaves, stems, and roots, in the first year after germination. The plant produces flowers, fruits, and seeds the second year. At the end of the second year, the plant dies. Red clover is an example of a biennial plant. Perennial plants grow year after year. Perennials produce flowers, fruit, and seeds each year. After they produce seeds, they go into a resting period called dormancy. This process is more noticeable in regions that have cold winter seasons, where perennials may stop growing completely for the winter. During the period of dormancy, the perennial slows down all its natural processes to protect itself from colder temperatures. When spring 5 Introduction to Grassland Management The two major groups of grasses are cool-season and Missouri has the right climate and amount of annual warm-season grasses. Cool-season grasses tend to grow rainfall for both cool-season and warm-season grasses. best during the spring and fall. These plants begin their Figure 2.2 shows how the growth periods of these two growing season when the soil temperature reaches 40° F, grass types complement each other and extend the length but optimum growth occurs when air temperatures fall in of green pasture production in Missouri. the 59° to 77° F range. They may remain green all winter, but during the summer months they tend to become Legumes brown and dormant. They may be annuals or perennials. Examples of cool-season grasses include Kentucky Legumes and grasses together make up the dominant plant bluegrass, orchardgrass, and smooth bromegrass. types found in grasslands. Both are used as forage crops and therefore are beneficial to agricultural production. Warm-season grasses are just the opposite, in that they Figure 2.3 shows characteristic legumes. Examples of grow best during periods of warm temperatures. These legumes include soybeans, alfalfa, clovers, and birdsfoot grasses are much more tolerant of heat and drought trefoil. than cool-season grasses. Their growing season begins when soil temperature reaches 60° F, and they grow best Legumes have several identifying characteristics. One during the summer when temperatures are in the 77° to characteristic of legumes is the fruit or pod that they 104° F range. They are dormant in the winter and do not produce. This pod has one chamber, with seeds lined in a begin to turn green until early summer. They also may be single row. The seed number and size varies for different annuals or perennials, Some examples of warm-season plants. All legumes have leaves that are alternate in grasses are indiangrass, big bluestem, and switchgrass. arrangement on the stem and are connected to the stem Figure 2.2 – Cool- and Warm-Season Grass Growth 6 Unit I – Grasslands and Grassland Plants Figure 2.3 – Characteristic Legumes by a stalk called a petiole. Unlike the grasses, venation in Forbs a legume consists of a network of veins rather than veins that run parallel to each other. Legumes may be annuals, Herbaceous (or not woody) plants that are neither perennials, or biennials. grasses or legumes are called forbs. Most forbs are broad- leafed, making it possible to distinguish them from grasses Most legumes have the unique ability to take nitrogen or grasslike plants. Forbs are not usually cultivated for from the air between soil particles and change it into agricultural production, but they commonly appear in a form of nitrogen that plants can use. This process is both pastures and native plant habitats. Many forbs have known as nitrogen fixation and is carried out by symbiotic value as wildlife food and cover or for prevention of soil bacteria found in nodules on the roots. This nitrogen erosion. Others are considered to be noxious weeds. helps decrease fertilizer needs, reduce costs, increase Forbs may be annuals, perennials, or biennials. Some yields, and enrich the soil. examples of forbs are sunflowers, thistle, and ragweed, which are pictured in Figure 2.4. Figure 2.4 – Characteristic Forbs 7 Introduction to Grassland Management Figure 2.5 – Characteristic Woody Plants Woody Plants Credits Woody plants are probably the easiest plants to Barnes, Robert F., Darrell A. Miller, and C. Jerry Nelson. identify in the grassland because of their tough, woody Forages, Volume I: An Introduction to Grassland Agriculture. (nonherbaceous) stems. They are either shrubs, vines, or 5th ed. Ames: Iowa State University Press, 1995. trees. Woody trees found in grasslands are almost always immature due to the nature and use of the grassland. They Coambes, Howard, John Jennings, and David E. Pitts. are kept small by animals that graze on terminal branches, Grassland Evaluation Contest Study Guide. University of by fires that stunt growth, by mechanical cutting, or by Missouri-Columbia: Instructional Materials Laboratory, chemical treatments carried out to maintain the grassland. 1997. Woody plants are perennials. Examples of woody plants found in grasslands include wild rose, redcedar, and elm, Hitchcock, A.S. Manual of the Grasses of the United States. shown in Figure 2.5. 2nd ed. 2 vols. New York: Dover Publications, Inc., 1971. Summary Humphrey, John Kevin. Plant Science. University of Missouri- Columbia: Instructional Materials Laboratory, 1991. Understanding plant types and life cycles will help in managing a grassland for many purposes. Grassland Rodekohr, Sherie, and Debi Waeckerle. Landscaping and plants may be annuals, biennials, or perennials; they may Turf Management. University of Missouri-Columbia: also be grasses, legumes, forbs, or woody plants. They are Instructional Materials Laboratory, 1990. important for the whole grassland habitat and its many uses. 8.